Conventionally, there is known a roadside apparatus of this kind described in the publication of JP-A-7-334786, for example.
In the roadside apparatus described in this document, the measurement data from a traveling vehicle, or mobile, is received by a road-to-vehicle communicating means. The measurement data received from each traveling vehicle is immediately sent directly to another road-information summarizing apparatus, e.g. center apparatus.
However, with such a conventional roadside apparatus, when sending the measurement data received from each mobile to the road-information collecting apparatus such as a center apparatus, no process is made to reduce the amount of data. In the event of a spread of the mobiles to send measurement data to a roadside apparatus, there encounters an increase of the data to be sent from the roadside apparatus to the road-information collecting apparatus in proportion to the increase in the number thereof. This raises a problem of transmission trouble in terms of the speed and capacity of transmission.